1. Field of the Invention
The present invention relates to a circuit with adjustable phase delay and a feedback voltage and a method for adjustable phase delay and a feedback voltage, and particularly to a circuit and a method that can utilize a delay setting unit, a phase delay signal generator, and a sample and hold unit to generate adjustable phase delay and a stable feedback voltage.
2. Description of the Prior Art
Please refer to FIG. 1 and FIG. 2. FIG. 1 is a diagram illustrating a thin film transistor liquid crystal display (TFT-LCD) generating ghost shadows due to long liquid crystal reaction time, and FIG. 2 is a diagram illustrating the thin film transistor liquid crystal display utilizing a scanning backlight to solve the ghost shadows due to the long liquid crystal reaction time. As shown in FIG. 1, a viewer can view ghost shadows at an interval T because the liquid crystal reaction time is longer and a backlight BL is continuously turned on when liquid crystals of the thin film transistor liquid crystal display are changed from gray level 0 to gray level 255, where VSYNC is a vertical synchronization signal of the thin film transistor liquid crystal display. Meanwhile, the thin film transistor liquid crystal display exhibits a gray color. As shown in FIG. 2, because a backlight BL of the scanning backlight is turned on according to the vertical synchronization signal VSYNC of the thin film transistor liquid crystal display, the viewer can not view the ghost shadows at the interval T because the backlight BL is not turned on when the liquid crystals of the thin film transistor liquid crystal display are changed from the gray level 0 to the gray level 255 (at the interval T). That is to say, the scanning backlight has phase delay to respond liquid crystal rotation time of the thin film transistor liquid crystal display. Thus, the scanning backlight not only can solve the ghost shadows of the thin film transistor liquid crystal display, but can also solve crosstalk between left eye images and right eye images of three-dimensional images when the thin film transistor liquid crystal display displays the three-dimensional images.
In the prior art, because a system needs to provide a plurality of pulse width modulation signals to the scanning backlight to achieve the phase delay, the system has a more complicated circuit layout and higher cost. In another prior art, because a system utilizes a microprocessor to control the phase delay in a digital method, the system has additional cost of the microprocessor. Thus, the above mentioned prior arts not only increase cost of the system, but also increase complexity of the circuit layout of the system, so the above mentioned prior arts are not the best choices for a user.